The correct answer is C) 2021.
The last census in India was conducted in 2021. The census is a survey of the population of India that is conducted every 10 years. The 2021 census was the 15th census of India. The census provides data on the population, age, sex, religion, language, literacy, and other characteristics of the population of India. The data from the census is used to plan for the development of the country.
Option A) 2001 is incorrect because the last census in India was conducted in 2021, not 2001.
Option B) 2011 is incorrect because the last census in India was conducted in 2021, not 2011.
Option D) 2023 is incorrect because the last census in India was conducted in 2021, not 2023.